Condeelis J S
J Cell Sci. 1977 Jun;25:387-402. doi: 10.1242/jcs.25.1.387.
Synthetic myosin thick filaments were formed from preparations of electrophoretically homogeneous myosin isolated from Chaos carolinensis and Amoeba proteus when dialysed to physiological ionic strength and pH. Myosin dialysed directly against low ionic strength buffers formed native-like thick filaments in the presence and absence of exogenous divalent cations. The average dimensions of the synthetic filaments grown under these conditions were 455 nm long and 16 nm wide with a distinct bare central zone 174 nm long. Myosin predialysed against EGTA-EDTA solutions at high ionic strength and then dialysed to low ionic strength formed native-like filaments only in the presence of 1mM Mg2+. 1 mM Ca2+ could not be substituted for Mg2+ under these conditions to achieve native-like filaments. Filaments grown from predialysed myosin in the absence of Mg2+ resembled EGTA-dissociated myosin filaments observed in EGTA-treated cytoplasm and were highly branched, poorly formed filaments lacking a distinct bare central zone. The average dimensions of the filaments grown from predialysed myosin in the absence of Mg2+ were 328 nm long, 13 nm wide with a bare central zone 111 nm long. Under the conditions tested, myosin isolated from these amoebae did not demonstrate a divalent cation requirement for thick filament formation. The results obtained with myosin isolated from the 2 organisms were identical.
当透析至生理离子强度和pH值时，从卡罗林裸变形虫和蛋白核变形虫中分离出的经电泳均一的肌球蛋白制剂形成了合成肌球蛋白粗丝。直接针对低离子强度缓冲液透析的肌球蛋白，无论有无外源二价阳离子，都会形成类似天然的粗丝。在这些条件下生长的合成丝的平均尺寸为长455nm，宽16nm，有一个174nm长的明显无丝区。在高离子强度下针对EGTA - EDTA溶液预透析，然后透析至低离子强度的肌球蛋白，仅在存在1mM Mg2+时形成类似天然的丝。在这些条件下，1mM Ca2+不能替代Mg2+以形成类似天然的丝。在没有Mg2+的情况下，由预透析的肌球蛋白生长的丝类似于在EGTA处理的细胞质中观察到的EGTA解离的肌球蛋白丝，是高度分支、形成不良的丝，没有明显的无丝区。在没有Mg2+的情况下，由预透析的肌球蛋白生长的丝的平均尺寸为长328nm，宽13nm，无丝区长111nm。在测试的条件下，从这些变形虫中分离出的肌球蛋白在形成粗丝时未表现出对二价阳离子的需求。从这两种生物体中分离出的肌球蛋白所获得的结果是相同的。
